Taming amp gain in single channel deluxe reverb build

[imo1]

I don’t have my notes in front of me(on tour) but the 6v6s were right at 420 and all of the preamps were pretty much right in spec with the deluxe schematic. So thinking 185-190 on v1, etc.
Nothing much higher or lower than spec.
My bias was taken off the hv winding and I implemented Merlin’s bias circuit, but used 10k pot and resistor.

Ok, thanks. I made another revision, with suggested current production Hammond power transformers which include the bias tap, and left the original DR bias supply. I would have thought that without the normal channel 12AX7 you'd have a bit higher voltages on the V1 plates at the same 6V6 plate voltage.

I used a PT that was specced for a Princeton. It worked perfectly. Plenty of juice for the single channel but was able to avoid the higher voltage

[lonote]

I don’t have the specs but don’t el84s need a good deal less gain to drive them then 6v6s? That would make sense.

I believe you are correct & that EL84s do require less gain.


And I even made a mental note to that effect when I was mapping this out, but misplaced the note...or the dog ate it.

[martin manning]

I used a PT that was specced for a Princeton. It worked perfectly. Plenty of juice for the single channel but was able to avoid the higher voltage

ok, I see it's in the first post, Classic Tone. The schematic is now updated with the Hammond equivalent.

[Roe]

grid resistors also help minimizing blocking distortion. and be careful with .1uf coupling caps in the PI combined with 220k bias splitters

On my project, I was able to experiment some yesterday with knocking back the PI input using a voltage divider (the 220K + an added 250K pot to ground) & made some progress. Somewhere around 40K-60K on the pot was working well.

The comment about the .1uF coupling caps stands out though, as I have both the .1's & the 220K bias feeds in this circuit. Not sure how I landed on that CC value, other than auto-pilot.

As I am finding this one too bassy & will sub in some different CC's next.

Seems like integrating the Fender preamp to the EL84s is more fussy that I expected.

Personally, I like 15nf with 220k bias splitters, but use at least 5k6 for grid resistors.

I have an amp on the bench that uses 47k grid resistors, which really seems to help with blocking distortion. this is a koch, which is known for its power and punchy response